Medical devices and/or procedures are used in many different branch vessels and require a wide variety in placement techniques. One example of a placement technique is through use of a deflectable sheath. Typically, a deflectable sheath is controlled at a proximal end of the catheter by a control handle that operates a pull wire to deflect the sheath. However, with conventional catheter steering mechanisms, it can be difficult to accurately position the catheters in certain body vessels, such as branch veins. For instance, the mechanisms are awkward or require the use of two hands. Other steering mechanisms require pull wires to be wound and unwound around a rotatable cam wheel, causing increased fatigue on the pull wires, and potentially shortening the life of the device. Furthermore, some deflectable catheters involve relatively large catheter sheaths. The larger sheaths can be difficult to manipulate within a patient, and have increased deflection forces, frustrating efforts of a physician attempting to control deflection angle during a procedure.